The coding of the various notches in a key in accordance with a predetermined numerical formula is standard industry practice. However, there are several different perameters upon which the formula is based and these perameters vary from one standard type of key to another. For example, in comparing two standard types of keys, the longitudinal separation between the notches may have a standard value for each of the keys but this separation distance may be different for the two types of keys. The ratio instead of being 1:1 might be 1.1:1 or might be 1.25:1, for example. Also for a given type of key a notch having two units of depth would be precisely twice as deep as a notch having one unit of depth, but the unit of depth value would not be the same as on another standard type of key. Here again the ratio instead of being 1:1 might be significantly greater or significantly less than that.
In providing key cutting machines which will cut key blanks in accordance with a particular numerical combination or code it has, therefore, been necessary to provide a different machine for each standard type of key. Thus a machine which will cut Schlage keys in accordance with the code would not be used for cutting Kwick-Set keys in accordance with the code, and vice versa.